Heat Recovery Multi-Split Air Conditioning System and Control Method

ABSTRACT

A heat recovery multi-split air conditioning system including: an indoor module, an outdoor module, and a hydraulic module. The outdoor module comprises a compressor, two four-way valves, three electronic expansion valves, an outdoor heat exchanger, an outdoor fan, and a subcooler. The hydraulic module includes a heat exchange water tank and a refrigerant flow path. An inlet of the refrigerant flow path is communicated with an outlet of the compressor. Four joints of the subcooler are respectively communicated with the outlet of the refrigerant flow path, an outdoor heat exchanger, an air return port of the compressor, and the indoor module. The system further includes a temperature acquiring module, a water tank temperature correction coefficient acquiring module, and a control module. In a hot water production mode, an opening degree of the third electronic expansion valve is adjusted.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. CN202210656370.5 filed on Jun. 10, 2022.

TECHNICAL FIELD

The present invention relates to the field of air conditioners, and specifically, to a heat recovery multi-split air conditioning system and a control method.

BACKGROUND

In a heat recovery multi-split machine system, when mainly employed in producing hot water, there is no subcooling in a liquid pipe, resulting in a gas-liquid two-phase state in a liquid pipe of an internal unit. After the internal unit is throttled, the temperature grows higher, resulting in poor air outlet effect.

When mainly employed in refrigeration, when a water tank temperature is high, most of the refrigerants are dissipated through an external unit rather than through a hydraulic module, resulting in a slower rise in water temperature; and when mainly employed in refrigeration, the refrigeration internal unit requires less energy demands, and the compressor output is less.

SUMMARY OF THE INVENTION

Regarding the above problems, the present invention provides a heat recovery multi-split air conditioning system and a control method, which can improve the subcooling degree of a liquid pipe.

The present invention provides a heat recovery multi-split air conditioning system, including an indoor module, an outdoor module, and a hydraulic module, where the outdoor module includes a compressor, a first four-way valve, a second four-way valve, multiple electronic expansion valves, an outdoor heat exchanger, and an outdoor fan; the hydraulic module includes a heat exchange water tank and a refrigerant flow path; the system further includes a subcooler, where four joints of the subcooler are respectively communicated with an outlet of the refrigerant flow path, the outdoor heat exchanger, an air return port of the compressor, and the indoor module; an inlet of the refrigerant flow path is communicated with an outlet of the compressor; the multiple electronic expansion valves comprise: a first electronic expansion valve disposed between the outdoor heat exchanger and the indoor module, a second electronic expansion valve disposed between an outlet of the refrigerant flow path and the first electronic expansion valve, and a third electronic expansion valve disposed between an outlet of the refrigerant flow path and a joint of the subcooler; the system further includes a temperature acquiring module configured to acquire a water tank temperature and a refrigerant liquid pipe temperature of the hydraulic module; a water tank temperature correction coefficient acquiring module, which obtains a water tank temperature correction coefficient; and a control module, where when mainly employed in producing hot water, the control module adjusts an opening degree of the third electronic expansion valve according to a comparison result between a different value among the water tank temperature, the water tank temperature correction coefficient, and the refrigerant liquid pipe temperature of the hydraulic module and a first preset value.

According to the technical solution, when mainly employed in producing hot water, a subcooling degree of an outdoor heat exchanger liquid pipe is judged according to the comparison result between the water tank temperature, the water tank temperature correction coefficient, and the refrigerant liquid pipe temperature of the hydraulic module and a first preset value. When the subcooling degree is insufficient, a third electronic expansion valve is opened to perform subcooling on the liquid pipe, so as to solve a problem that when mainly employed in producing hot water, there is no subcooling degree in the liquid pipe, resulting in a gas-liquid two-phase state in a liquid pipe of an internal unit and a high temperature in the internal unit after throttling, resulting in poor air outlet effect, effectively avoiding insufficient subcooling when the water temperature rises.

In an optional technical solution of the present invention, a temperature acquiring module is further configured to acquire a pre-subcooling temperature of the refrigerant before entering a subcooling pipe of the indoor module and a post-subcooling temperature of the refrigerant after entering the subcooling pipe of the indoor module.

The control module is configured to: when the difference value of the water tank temperature, the water tank temperature correction coefficient, and the refrigerant liquid pipe temperature of the hydraulic module is within a prescribed temperature range, adjust the opening degree of the third electronic expansion valve according to a comparison result between a difference value of the pre-subcooling temperature and the post-subcooling temperature and a second preset value.

According to the technical solution, it is beneficial to ensure the subcooling degree in the outdoor module liquid pipe, effectively avoiding insufficient subcooling degree when the water temperature rises.

In an optional technical solution of the present invention, a temperature acquiring module is configured to acquire an outdoor ambient temperature; in a refrigeration mode, after the outdoor fan runs a specified time length according to a maximum fan speed corresponding to the outdoor ambient temperature, the control module adjusts an operating fan speed of the outdoor fan according to the temperature of the outlet in a lowest path of the condenser.

According to the technical solution, by reducing the operating fan speed of the outdoor fan, the system's waste heat is transferred to the hydraulic module, increasing the efficiency of heat recovery.

In an optional technical solution of the present invention, in a refrigeration mode, an operating energy demand of the compressor is NC1=NC+€1+€2, NC is an original energy demand of the compressor; €1 is a corrected value for a refrigeration internal unit, and €2 is a corrected value for a temperature difference of hot water.

According to the technical solution, adjusting the operating energy demand of the compressor through the corrected value of the refrigeration internal unit and the corrected value of the hot water temperature difference is beneficial for increasing the output of the compressor and improving the efficiency of hot water production at low water temperatures.

In an optional technical solution of the present invention, a temperature acquiring module is configured to acquire a temperature of an outlet of an evaporator; in a refrigeration mode, the control module adjusts a corrected value of the refrigeration internal unit according to a comparison result between the temperature of the outlet of the evaporator and a third preset value.

According to the technical solution, it is beneficial to increase the output of the compressor and increase the rising speed of the water temperature.

In an optional technical solution of the present invention, a temperature acquiring module is configured to acquire a water tank temperature; during refrigeration, the control module adjusts the corrected value of the hot water temperature difference according to a comparison result between a set temperature of the water tank and the water tank temperature and a fourth preset value.

According to the technical solution, it is beneficial to increase the output of the compressor and increase the rising speed of the water temperature.

In an optional technical solution of the present invention, in a hot water production mode, a refrigerant returns to the compressor after sequentially passing through the compressor, a refrigerant flow path of the hydraulic module, the second electronic expansion valve, the first electronic expansion valve, the outdoor heat exchanger, and the first four-way valve; and/or a refrigerant returns to the compressor after sequentially passing through the compressor, a refrigerant flow path of the hydraulic module, the third electronic expansion valve, and the subcooler.

In an optional technical solution of the present invention, in a refrigeration mode, a refrigerant returns to the compressor after sequentially passing through the compres sor, the second four-way valve, the outdoor heat exchanger, the first electronic expansion valve, the subcooler, the indoor module, and the first four-way valve.

The present invention further provides a method for controlling a heat recovery multi-split air conditioning system, including the following steps: acquiring a water tank temperature and a refrigerant liquid pipe temperature of the hydraulic module; acquiring a water tank temperature correction coefficient; and when mainly employed in producing hot water, adjusting an opening degree of the third electronic expansion valve according to a comparison result between a difference value of the water tank temperature, the water tank temperature correction coefficient, and the refrigerant liquid pipe temperature of the hydraulic module, and a first preset value.

In an optional technical solution of the present invention, it further includes: in a refrigeration mode, acquiring an outdoor ambient temperature and a temperature of an outlet in a lowest path of a condenser; after the outdoor fan runs a specified time length according to a maximum fan speed corresponding to the outdoor ambient temperature, the control module adjusts an operating fan speed of the outdoor fan according to the temperature of the outlet in a lowest path of the condenser; and/or

acquiring a temperature of an outlet of an evaporator, where the control module adjusts an operating energy demand of the compressor according to a comparison result between a temperature of the outlet of the evaporator and a third preset value; and adjusts an operating energy demand of the compressor according to a comparison result between a difference value of a set temperature of the water tank and the water tank temperature and a fourth preset value.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic structural diagram of a heat recovery multi-split air conditioning system in an implementation of the present invention;

FIG. 2 is a schematic structural diagram of a system for controlling a heat recovery multi-split air conditioning system in an implementation of the present invention; and

FIG. 3 is a schematic flowchart of a method for controlling a heat recovery multi-split air conditioning system in an implementation of the present invention.

REFERENCE NUMERALS

-   -   an indoor module 1; an indoor heat exchanger 11; an outdoor         module 2; a compressor 21; a first four-way valve 22; a second         four-way valve 23; an outdoor heat exchanger 24; an outdoor fan         25; a subcooler 26; a gas-liquid separator 27; a hydraulic         module 3; a heat exchange water tank 31; a temperature T2B of an         outlet of an evaporator; a temperature T3 of an outlet in a         lowest path of the condenser; a refrigerant liquid pipe         temperature T3C of the hydraulic module, an outdoor ambient         temperature T4; a water tank temperature T5; a pre-subcooling         temperature T6; a post-subcooling temperature T7; a set         temperature TS of a water tank; an original energy demand Nc of         a refrigeration internal unit; a corrected value €1 of the         refrigeration internal unit; a corrected value €2 for a         temperature difference of hot water; an operating energy demand         NC1 of the compressor; a first electronic expansion valve EXV1;         a second electronic expansion valve EXV2; a third electronic         expansion valve EXV3; a first one-way valve 51; a second one-way         valve 52; a third one-way valve 53.

DETAILED DESCRIPTION

A clear and complete description of the technical solutions in the embodiments of the present invention will be described below, in conjunction with the accompanying drawings. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

As shown in FIGS. 1 and 2 , the present invention provides a heat recovery multi-split air conditioning system, including: an indoor module 1, an outdoor module 2, and a hydraulic module 3, where the indoor module 1 includes multiple parallel indoor heat exchangers 11; the outdoor module 2 includes a compressor 21, a first four-way valve 22, a second four-way valve 23, multiple electronic expansion valves, an outdoor heat exchanger 24, an outdoor fan 25, and a subcooler 26; the hydraulic module 3 includes a heat exchange water tank 31 and a refrigerant flow path; the multiple electronic expansion valves include a first electronic expansion valve EXV1 disposed between the outdoor heat exchanger 24 and the indoor module 1, a second electronic expansion valve EXV2 disposed between an outlet of a refrigerant flow path and the first electronic expansion valve EXV1, and a third electronic expansion valve EXV3 disposed between the outlet of the refrigerant flow path and the subcooler 26; an inlet of the refrigerant flow path is communicated with an outlet of the compressor 21, and other joints of the subcooler 26 are respectively communicated with the outdoor heat exchanger 24, an air return port of the compressor 21, and the indoor module 1.

A control system 4 is further included. The control system 4 includes a temperature acquiring module 41 configured to acquire a water tank temperature T5 and a the refrigerant liquid pipe temperature T3C of the hydraulic module (for example, acquiring by means of a temperature sensor indicated by P5 and P3C in FIG. 1 ); a water tank temperature correction coefficient acquiring module 42, configured to acquire a water tank temperature correction coefficient Δt and makes modification according to a structural form of the water tank and test parameters (generally 5° C.); and a control module 43, where when employed mainly in producing hot water, the control module 43 adjusts an opening degree of the third electronic expansion valve EXV3 according to a comparison result between a difference value of the water tank temperature T5, the water tank temperature correction coefficient Δt, and the refrigerant liquid pipe temperature T3C of the hydraulic module and a first preset value.

By means of the above method, when mainly employed in producing hot water, a subcooling degree of an outdoor heat exchanger 24 liquid pipe is judged according to the comparison result between the water tank temperature T5, the water tank temperature correction coefficient Δt, and the refrigerant liquid pipe temperature T3C of the hydraulic module and a first preset value. When the subcooling degree is insufficient, a third electronic expansion valve EXV3 is opened to perform subcooling on the liquid pipe, so as to solve a problem that when mainly employed in producing hot water, there is no subcooling degree in the liquid pipe, resulting in a gas-liquid two-phase state in a liquid pipe of an internal unit and a high temperature in the internal unit after throttling, resulting in poor air outlet effect, effectively avoiding insufficient subcooling degree when the water temperature rises.

Specifically, joints d, e, and s of the first four-way valve 22 are respectively connected to an air exhaust end of the compressor 21, a first end of the indoor module 1, and an air return end of the compressor 21; a joint c of the first four-way valve 22 is connected to the joint s through a short circuit by means of a first capillary pipe; joints g, h, and i of the second four-way valve 23 are respectively connected to an air exhaust end of the compressor 21, an outdoor heat exchanger 24, and an air return end of the compressor 21; a joint f of the second four-way valve 23 is connected to the joint i through a short circuit by means of a second capillary pipe; one end of a refrigerant flow path of a heat exchange water tank 31 is connected to the air exhaust end of the compressor 21; the other end of the refrigerant flow path of the heat exchange water tank 31 is in a bypass connection between the first electronic expansion valve EXV1 and the indoor heat exchanger 11 via a first one-way valve 51; a second one-way valve 52 disposed between the first electronic expansion valve EXV1 and the outdoor heat exchanger 24, and a third one-way valve 53 disposed between the subcooler 26 and the indoor module 1 are further included; the first one-way valve 51 controls a unidirectional flow of a refrigerant from the heat exchange water tank 31 to the subcooler 26 and/or the outdoor heat exchanger 24; the second one-way valve 52 controls a unidirectional flow of a refrigerant from the outdoor heat exchanger 24 to the first electronic expansion valve EXV1; and the third one-way valve 53 controls a unidirectional flow of a refrigerant from the indoor module 1 to the third electronic expansion valve EXV3.

Further, a gas-liquid separator 27 is included. The refrigerant returns to the air exhaust end of the compressor 21 after passing through a second four-way valve 23 and a gas-liquid separator 27. A joint of the subcooler 26 returns to the air exhaust end of the compressor 21 after passing through the gas-liquid separator 27.

In an implementation of the present invention, the temperature acquiring module 41 is further configured to acquire a pre-subcooling temperature T6 of the refrigerant before entering a subcooling pipe of the indoor module and a post-subcooling temperature T7 of the refrigerant after entering the subcooling pipe of the indoor module (for example, acquiring by means of a temperature sensor indicated by P6 and P7 in FIG. 1 ). The control module 43 is configured to: adjust an opening degree of the third electronic expansion valve EXV3 according to the difference value between the pre-subcooling temperature T6 and the post-subcooling temperature T7 when the difference value of the water tank temperature T5, the water tank temperature correction coefficient Δt, and the refrigerant liquid pipe temperature T3C of the hydraulic module is within a prescribed temperature range. By means of the above method, it is beneficial to ensure the subcooling degree in the outdoor module liquid pipe, effectively avoiding insufficient subcooling degree when the water temperature rises.

Specifically, when T5−Δt−T3C≥5° C., the EXV3 is closed; when T5−Δt−T3C<2° C., the EXV3 is completely open; when 2° C.≤T5−Δt−T3C<5° C. and T6−T7≥7° C., the EXV3 is closed by 16P; when T6−T7<2° C., the EXV3 is opened by 16P; and when 2° C.≤T6−T7<7° C., the EXV3 remains unchanged.

In a preferred implementation of the present invention, the temperature acquiring module 41 is configured to acquire an outdoor ambient temperature T4; in a refrigeration mode, after the outdoor fan 25 runs a specified time length according to a maximum fan speed corresponding to the outdoor ambient temperature T4, the control module 43 adjusts an operating fan speed of the outdoor fan 25 according to the temperature T3 of the outlet in a lowest path of the condenser. In the implementation of the present invention, by reducing the operating fan speed of the outdoor fan 25, the system's waste heat is transferred to the hydraulic module 3, increasing the efficiency of heat recovery.

Specifically, the fan speed of the outdoor fan 25 has a maximum level and a minimum level according to the difference of the outdoor ambient temperature T4, as shown in the following table:

Temperature (° C.) Min Max 37 ≤ T4 W4 W8 29 ≤ T4 < 36 W3 W7 17 ≤ T4 < 29 W2 W7  5 ≤ T4 < 17 W2 W6

During operation, the outdoor fan 25 first runs for 30 S at a maximum fan speed level according to the outdoor ambient temperature T4, and then the fan speed of the outdoor fan 25 automatically adjusts according to the temperature T3 of the outlet in a lowest path of the condenser; when in a refrigeration mode, taking the outdoor heat exchanger 24 as a condenser, the temperature T3 of the outlet in a lowest path of the condenser is the temperature of the outlet in a lowest path of the outdoor heat exchanger 24;

-   -   when T3≥60° C., the fan speed runs at W8; when T3<58° C., it is         normally controlled;     -   when T3≥58° C., the fan speed increases 1/20 s (till the fan         speed reaches W8); when T3<56° C., it is normally controlled;     -   when T3≥52° C., the fan speed increases 1/20 s (till the         corresponding maximum fan speed in the interval);     -   when T3≥45° C., the fan speed remains unchanged;     -   when T3<45° C., the fan speed decreases 1/20 s (till the         corresponding minimum fan speed in the interval).

In a preferred implementation of the present invention, in a refrigeration mode, an operating energy demand of the compressor 21 is NC1=NC+€1+€2, NC is an original energy demand of the compressor 21; €1 is a corrected value for a refrigeration internal unit, and €2 is a corrected value for a temperature difference of hot water. In the implementation of the present invention, the operating energy demand of the compressor 21 is adjusted by means of the corrected value €1 for the refrigeration internal unit and the corrected value €2 for the temperature difference of hot water, which facilitates increasing the output of the compressor 21 and improves the efficiency of producing hot water under a low water temperature.

In a preferred implementation of the present invention, a temperature acquiring module 41 is configured to acquire an temperature T2B of the outlet of the evaporator; during refrigeration, the control module 43 adjusts the corrected value €1 for the refrigeration internal unit according to a comparison result between the temperature T2B of the outlet of the evaporator and a third preset value; during refrigeration, as an evaporator, the indoor heat exchanger 11 is used as the evaporator, and the temperature T2B of the outlet of the evaporator is the temperature of the outlet of the indoor heat exchanger 11. By means of the above method, it is beneficial for increasing the output of the compressor 21 and improving the rising speed of the water temperature. Specifically, when T2B≥12° C., €1+1, which is detected every two minutes, with a maximum of €1=8; when T2B<6° C., €1-1, which is detected every two minutes, with a maximum of €1=4; When 6° C.≤T2B<12° C., 1 remains in the previous state.

In a preferred implementation of the present invention, the temperature acquiring module 41 is configured to acquire the water tank temperature T5; during refrigeration, the control module 43 adjusts the corrected value €2 for the temperature difference of hot water according to a comparison result between a difference value of the set temperature of the water tank and the water tank temperature T5 and a fourth preset value. By means of the above method, it is beneficial for increasing the output of the compressor 21 and improving a rising speed of the water temperature. Specifically, when TS-T5≥5° C.; €2+1, which increases once every 2 minutes, with a maximum of €2=10; when 2° C.≤TS-T5; €2=0; when 2° C.<TS-T5<5° C.; €2 remains in the previous state.

In a preferred implementation of the present invention, in a hot water production mode, the refrigerant returns to the compressor 21 after sequentially passing through the compressor 21, a refrigerant flow path of the hydraulic module 3 (a refrigerant inlet and a refrigerant outlet of the heat exchange water tank 31), a second electronic expansion valve EXV2, a first electronic expansion valve EXV1, an outdoor heat exchanger 24, and a first four-way valve 22, where the second electronic expansion valve EXV2 and; and/or the refrigerant returns to the compressor 21 after sequentially passing through the compressor 21, the refrigerant flow path of the hydraulic module 3, the third electronic expansion valve EXV3, the subcooler 26, and the gas-liquid separator 27.

In a preferred implementation of the present invention, in a refrigeration mode, the refrigerant returns to the compressor 21 after sequentially passing through the compressor 21, the second four-way valve 23, the outdoor heat exchanger 24, the first electronic expansion valve EXV1, the subcooler 26, the indoor module 1, the first four-way valve 22, and the gas-liquid separator 27.

In a preferred implementation of the present invention, some refrigerants of the outlet of the subcooler 26 are directly connected to the outlet of the gas-liquid separator 27 via a first branch pipeline, and the first branch pipeline is equipped with a third capillary pipe and an electromagnetic valve SV1. The refrigerant after subcooling enters the gas-liquid separator 27 via the first branch pipeline and returns to the compressor 21, which is beneficial to reduce the exhaust temperature of the compressor 21 and prevent the exhaust temperature of the compressor 21 from being too high.

In a preferred implementation of the present invention, an air exhaust end of the compressor 21 is disposed with a second branch pipeline, which is connected to an inlet of the gas-liquid separator 27, and the second branch pipeline is equipped with a fourth capillary pipe and an electromagnetic valve SV2.

As shown in FIG. 3 , the present invention further provides a method for controlling the above heat recovery multi-split air conditioning system, including the following steps: acquiring a water tank temperature T5 and a the refrigerant liquid pipe temperature T3C of the hydraulic module; acquiring a water tank temperature correction coefficient Δt; when mainly employed in producing hot water, an opening degree of the third electronic expansion valve EXV3 is adjusted according to a comparison result between a difference value of the water tank temperature T5, the water tank temperature correction coefficient Δt, and the refrigerant liquid pipe temperature T3C of the hydraulic module and a first preset value.

In a preferred implementation of the present invention, it further includes: in a refrigeration mode, acquiring an outdoor ambient temperature T4 and a temperature T3 of an outlet in a lowest path of the condenser; after the outdoor fan 25 runs a specified time length according to a maximum fan speed corresponding to the outdoor ambient temperature T4, the control module 43 adjusts an operating fan speed of the outdoor fan 25 according to the temperature T3 of the outlet in a lowest path of the condenser.

In a preferred implementation of the present invention, it further includes: acquiring a temperature T2B of the outlet of the evaporator an outlet; the control module 43 adjusts an operating energy demand of the compressor 21 according to a comparison result between a temperature T2B of an outlet of the evaporator and a third preset value; and/or, adjusts an operating energy demand of the compressor 21 according to a comparison result between a difference value of a set temperature of the water tank and the water tank temperature T5 and a fourth preset value.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. 

1. A heat recovery multi-split air conditioning system, comprising: an indoor module, an outdoor module, and a hydraulic module, wherein the outdoor module comprises a compressor, a first four-way valve, a second four-way valve, multiple electronic expansion valves, an outdoor heat exchanger, and an outdoor fan; the hydraulic module comprises a heat exchange water tank and a refrigerant flow path; further comprising a subcooler, wherein four joints of the subcooler are respectively communicated with an outlet of the refrigerant flow path, the outdoor heat exchanger, an air return port of the compressor, and the indoor module; an inlet of the refrigerant flow path is communicated with an outlet of the compressor; the multiple electronic expansion valves comprise: a first electronic expansion valve disposed between the outdoor heat exchanger and the indoor module, a second electronic expansion valve disposed between an outlet of the refrigerant flow path and the first electronic expansion valve, and a third electronic expansion valve disposed between an outlet of the refrigerant flow path and a joint of the subcooler; further comprising: a temperature acquiring module configured to acquire a water tank temperature and a refrigerant liquid pipe temperature of the hydraulic module; a water tank temperature correction coefficient acquiring module, which obtains a water tank temperature correction coefficient; and a control module, wherein when in a hot water production mode, the control module adjusts an opening degree of the third electronic expansion valve according to a comparison result between a different value among the water tank temperature, the water tank temperature correction coefficient, and the refrigerant liquid pipe temperature of the hydraulic module and a first preset value.
 2. The heat recovery multi-split air conditioning system according to claim 1, wherein the temperature acquiring module is further configured to acquire a pre-subcooling temperature of the refrigerant before entering a subcooling pipe of the indoor module and a post-subcooling temperature of the refrigerant after entering the subcooling pipe of the indoor module; the control module is configured to: when the difference value of the water tank temperature, the water tank temperature correction coefficient, and the refrigerant liquid pipe temperature of the hydraulic module is within a prescribed temperature range, adjust the opening degree of the third electronic expansion valve according to a comparison result between a difference value of the pre-subcooling temperature and the post-subcooling temperature and a second preset value.
 3. The heat recovery multi-split air conditioning system according to claim 1, wherein the temperature acquiring module is configured to acquire an outdoor ambient temperature and a temperature of an outlet in a lowest path of a condenser; in a refrigeration mode, after the outdoor fan runs a specified time length according to a maximum fan speed corresponding to the outdoor ambient temperature, the control module adjusts an operating fan speed of the outdoor fan according to the temperature of the outlet in a lowest path of the condenser.
 4. The heat recovery multi-split air conditioning system according to claim 1, wherein in a refrigeration mode, an operating energy demand of the compressor is NC1=NC+€1+€2, NC is an original energy demand of the compressor; €1 is a corrected value for a refrigeration internal unit, and €2 is a corrected value for a temperature difference of hot water.
 5. The heat recovery multi-split air conditioning system according to claim 4, wherein the temperature acquiring module is configured to acquire a temperature of an outlet of an evaporator; in a refrigeration mode, the control module adjusts a corrected value of the refrigeration internal unit according to a comparison result between the temperature of the outlet of the evaporator and a third preset value.
 6. The heat recovery multi-split air conditioning system according to claim 4, wherein the temperature acquiring module is configured to acquire a water tank temperature; during refrigeration, the control module adjusts the temperature difference of hot water according to a comparison result between a set temperature of the water tank and the water tank temperature and a fourth preset value.
 7. The heat recovery multi-split air conditioning system according to claim 3, wherein in a hot water production mode, a refrigerant returns to the compressor after sequentially passing through the compressor, a refrigerant flow path of the hydraulic module, the second electronic expansion valve, the first electronic expansion valve, the outdoor heat exchanger, and the first four-way valve; and/or a refrigerant returns to the compressor after sequentially passing through the compressor, a refrigerant flow path of the hydraulic module, the third electronic expansion valve, and the subcooler.
 8. The heat recovery multi-split air conditioning system according to claim 4, wherein in a refrigeration mode, a refrigerant returns to the compressor after sequentially passing through the compressor, the second four-way valve, the outdoor heat exchanger, the first electronic expansion valve, the subcooler, the indoor module, and the first four-way valve.
 9. A method for controlling a heat recovery multi-split air conditioning system according to claim 1, comprising the following steps: acquiring a water tank temperature and a refrigerant liquid pipe temperature of the hydraulic module; acquiring a water tank temperature correction coefficient; acquiring a water tank temperature correction coefficient; when mainly employed in producing hot water, the control module adjusts an opening degree of the third electronic expansion valve according to a comparison result between a difference value of the water tank temperature, the water tank temperature correction coefficient, and the refrigerant liquid pipe of the hydraulic module temperature, and a first preset value.
 10. The method for controlling a heat recovery multi-split air conditioning system according to claim 9, further comprising: in a refrigeration mode, acquiring an outdoor ambient temperature and a temperature of an outlet in a lowest path of a condenser; after the outdoor fan runs a specified time length according to a maximum fan speed corresponding to the outdoor ambient temperature, the control module adjusts an operating fan speed of the outdoor fan according to the temperature of the outlet in a lowest path of the condenser; and/or acquiring a temperature of an outlet of an evaporator, wherein the control module adjusts an operating energy demand of the compressor according to a comparison result between a temperature of an outlet of the evaporator and a third preset value; and adjusts an operating energy demand of the compressor according to a comparison result between a difference value of a set temperature of the water tank and the water tank temperature and a fourth preset value. 